Monday, April 22, 2013

Personal Type I error rates

As usual at the beginning of the week, this blog presents something in a lighter vein. However, this week we depart from phylogenetic networks in the strict sense, and take a humorous look at the broader statistical life of biologists.

Statistics is a curious thing, which allows scientists to make probability errors of two types: Type I (also known as false positives) and Type II (also known as false negatives). Importantly, these errors can accumulate in any one experiment, so that we can also recognize an Experimentwise Error Rate, which is the sum of the individual errors associated with each experimental hypothesis test.

However, what is not widely recognized is that these errors apply in life, as well. In particular, biologists accumulate statistical errors throughout their lives, so that we all have a Personal Lifetime Error Rate.

I once wrote a tongue-in-cheek article about the accumulation of Type I errors throughout the working life of a biological scientist, and the consequences for the experiments conducted by that scientist. This article appeared in 1991 in the Bulletin of the Ecological Society of Australia 21(3): 49–53, which means that I used an ecologist as my specific example of a biologist. The principle applies to all biologists, however.